What every physician needs to know:

Pleural fluid drained by thoracentesis commonly has a bloody appearance. A hematocrit performed on the pleural fluid can assist diagnostic evaluation of the patient.

Bloody pleural fluid with a hematocrit or greater than or equal to 50 percent of the peripheral blood hematocrit is termed a hemothorax, however lower pleural fluid hematocrit of 25-50% can be seen with haemodilution in case of long-standing hemothorax. Most patients who develop a pleural effusion secondary to blunt or penetrating chest trauma have a hemothorax.

If the hematocrit is less than 5 percent, the bloody appearance of the pleural fluid usually does not impart any diagnostic value.

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Bloody pleural fluid that has an erythrocyte count of greater than 100,000 cells/µl is termed a hemorrhagic effusion. When trauma is excluded, the presence of a hemorrhagic pleural effusion is usually due to malignancy, pulmonary embolism with infarction, benign asbestos pleural effusion, or post-cardiac injury syndrome.


Hemorrhagic pleural effusions and hemothoraces occur as a result of traumatic, iatrogenic, or non-traumatic etiologies:


  • blunt of penetrating chest trauma


  • Pleural procedures (thoracentesis, tube thoracostomy insertion, pleural biopsy)

  • Cardiothoracic surgery

  • Placement of central venous lines

  • Extra-vascular migration of central venous line


  • Malignancy

  • Pulmonary embolism with pulmonary infarction

  • Anticoagulant therapy

  • Bleeding diathesis

  • Spontaneous hemopneumothorax

  • Aortic dissection or rupture

  • Aneurysm rupture or dissection of internal mammary artery

  • Post-cardiac injury syndrome

  • Infections such as dengue hemorrhagic fever, pulmonary tuberculosis

  • Thoracic endometriosis with catamenial hemothorax

  • Vascular and connective tissue anomalies (Ehlers-Danlos type 4, neurofibromatosis, hereditary hemorrhagic telangiectasis)

  • Exostoses

  • Catamenial hemothorax

  • Extralobar pulmonary sequestration

  • Extramedullary hematopoiesis

  • Congenital diseases, such as Ehlers-Danlos type 4, neurofibromatosis, hereditary hemorrhagic telangiectasis, and Bean’s blue rubber nevus syndrome

Are you sure your patient has hemorrhagic pleural effusions or hemothorax? What should you expect to find?

The symptoms presented by patients with hemorrhagic pleural effusions and hemothoraces vary depending on the underlying etiology of intrapleural bleeding and the rate of accumulation and volume of pleural blood. The symptoms of the underlying etiology, such as chest pain in patients with blunt chest trauma, often dominate the clinical presentation.

Patients with non-traumatic hemorrhagic effusions usually present with progressive dyspnea with variable onset that depends on the rate of accumulation and the volume of pleural fluid. Some patients may have co-existing pleuritic chest pain.

Patients with traumatic hemothoraces may rapidly accumulate 3-4 L of blood in hemothorax, causing hypotension and other signs of hemorrhagic shock that typically do not occur with non-traumatic hemorrhagic effusions. Physical findings of both hemorrhagic effusions and hemothoraces include dullness to percussion, decreased breath sounds, and shift of the trachea to the contralateral side.

Presence of a pleural effusion following trauma or a rapidly enlarging pleural effusion following a pleural procedure suggests the presence of a hemothorax.

Beware: there are other diseases that can mimic hemorrhagic pleural effusions or hemothorax.

It takes only 10,000 erythrocytes/µl to impart a bloody appearance to pleural fluid. Transudative effusions that are due to congestive heart failure may have bloody effusions with cell counts below this level, which does not impart any diagnostic import, so it is important to establish that the erythrocyte count is higher than 100,000 cells/µl to diagnose a hemorrhagic effusion or to establish that the pleural fluid hematocrit is greater than 50 percent of the peripheral blood hematocrit to diagnose a hemothorax.

How and/or why did the patient develop hemorrhagic pleural effusions or hemothorax?

Vascular injury that is due to penetrating and blunt chest trauma is considered the most common mechanism for a hemothorax to develop. Approximately 40 percent of patients with blunt chest trauma develop hemothorax.

Iatrogenic causes of vascular injury occur following pleural procedures, lung biopsies, cardiac surgery, and extra-vascular migration of a central venous catheter.

The use of anticoagulant therapy, antifibrinolytic therapy, and intrinsic bleeding diathesis increase the inherent risk of a hemothorax. Similarly, vascular and connective tissue anomalies increase the risk for a hemothorax.

Which individuals are at greatest risk of developing hemorrhagic pleural effusions or hemothorax?

Individuals with blunt/penetrating chest trauma or vascular injury following pleural procedures, transthoracic lung biopsy, pleural biopsy, or post-cardiothoracic surgery; those who use anticoagulant therapy; and those with a history of known or suspected cancer, prior asbestos exposure, or a history of bleeding disorders are at greatest risk of developing hemorrhagic pleural effusions or hemothorax.

What laboratory studies should you order to help make the diagnosis, and how should you interpret the results?


  • CBC with platelet count

  • Basic metabolic profile with liver function tests

  • PT

  • INR

  • aPTT

Pleural fluid:

  • pH

  • Total protein

  • LDH

  • Glucose

  • Cell count with differential

  • Hematocrit

  • Cytology if there is concern about pleural malignancy

What imaging studies will be helpful in making or excluding the diagnosis of hemorrhagic pleural effusions or hemothorax?

A chest radiograph is useful, although it may miss a small hemothorax in 21 percent of patients following chest trauma, as at least 250 ml of fluid is required to obliterate costophrenic angle in well-penetrated upright chest radiographs.

Chest ultrasonography has been reported to have good sensitivity and very high specificity. Ultrasonography may reveal the “hematocrit sign” when cellular components of an effusion settle to the dependent regions of a pleural effusion, suggesting a hemothorax.

Chest-computed tomography with contrast may delineate the injured vessel and presence of hematocrit sign. High attenuation of pleural fluid in CT chest (Hounsfield unit [HU] of >15.6) can differentiate hemothorax from pleural effusions and empyema with excellent accuracy.

What non-invasive pulmonary diagnostic studies will be helpful in making or excluding the diagnosis of hemorrhagic pleural effusions or hemothorax?

No non-invasive studies other than chest imaging assist the diagnosis of intrapleural bleeding, which requires thoracentesis to confirm.

What diagnostic procedures will be helpful in making or excluding the diagnosis of hemorrhagic effusion or hemothorax?

Although imaging studies and the clinical circumstances may suggest a hemorrhagic effusion or hemothorax, thoracentesis with pleural fluid analysis is necessary to confirm these diagnoses. If pleural fluid analysis identifies bloody fluid but does not otherwise establish an etiology of intrapleural bleeding, medical thoracoscopy or video-assisted surgical thoracoscopy may be needed to establish underlying diagnoses, such as catamenial hemothorax and extramedullary hematopoieses.

What pathology/cytology/genetic studies will be helpful in making or excluding the diagnosis of hemorrhagic pleural effusions or hemothorax?

Cytology performed on pleural fluid can confirm the presence of a malignant pleural effusion. Genetic studies can be performed in cases of genetic diseases that predispose patients to a hemothorax.

If you decide the patient has hemorrhagic pleural effusions or hemothorax, how should the patient be managed?

The treatment of choice for a hemothorax is immediate insertion of a large-bore chest tube (size 28F to 36F). Chest tube insertion allows for complete evacuation of blood from the pleural space, stops the bleeding from pleural lacerations, allows quantification of the amount of bleeding, decreases the incidence of subsequent empyema because retained blood products are a good culture medium, removes pleural blood, and decreases risk of a fibrothorax. The chest tube should be removed once bleeding is controlled with pleural fluid drainage less than 50 ml over six hours.

Immediate thoracotomy is indicated for massive hemorrhage, as defined by an initial chest tube output greater than 1500 mL or continued pleural hemorrhage of greater than 200 mL/hour for several hours, suspected aortic injury or cardiac injury, sucking chest wounds, or major bronchial air leaks.

Patients on anticoagulation therapy should be treated to normalize their coagulopathy. Other bleeding risk factors should also be reversed.

Retained hemothorax puts patients at risk for development of empyema. Consider VATS for retained blood clots that occupy at least a third of the hemithorax between two and four days after initial injury. If VATS is not readily available for removal of retained blood clots, intrapleural fibrinolytics can be considered if it is performed within ten days of the initial injury.

Risks of therapy for hemothoraces include complications of chest tube insertion (including intercostal nerve and vessel injury and pleural space infection), the risks associated with general anesthesia (VATS carries a lower risk of morbidity and mortality than does thoracotomy, but both require general anesthesia), and an increase in the risk of pleural space bleeding from intrapleural fibrinolytics.

The treatment for hemorrhagic effusions depends on the underlying cause of the pleural bleeding.

What is the prognosis for patients managed in the recommended ways?

The four main complications of a hemothorax are the consequences of hypovolemia and hypovolemic shock, the retention of blood clots, empyema (empiric antibiotics are given in the setting of a traumatic hemothorax to reduce empyema and pneumonia), and fibrothorax (a delayed complication that can be successfully managed with decortication many months after insult). The presence of a malignant pleural effusion carries the worst long-term prognosis when one considers other causes of a bloody pleural effusion.

What other considerations exist for patients with hemorrhagic pleural effusions or hemothorax?

Genetic counseling should be considered for those with vascular or connective tissue anomalies that predispose them to development of a hemothorax.

What’s the Evidence?

Stafford, RE, Linn, J, Washington, L.. “Incidence and management of occult hemothoraces”. Am J Surg. vol. 192. 2006. pp. 722-6. (This study looked at 410 patients with chest trauma using chest radiographs and chest computed tomography for the presence of hemothorax. Chest radiograph missed hemothorax in 21 percent of cases.)

Sanabria, A, Valdivieso, E, Gomez, G, Echeverry, G.. “Prophylactic antibiotics in chest trauma: a meta-analysis of high-quality studies”. World J Surg. vol. 30. 2006. pp. 1843-7. (A meta-analysis of prophylactic antibiotics given for trauma-related hemothorax, establishing that antibiotics should be given; however, the ideal duration of antibiotic administration is unknown.)

Ng, CSH, Yim, AP.. “Spontaneous hemopneumothorax”. Curr Opin Pulm Med. vol. 12. 2006. pp. 273-7. (An excellent review of spontaneous hemopneumothorax.)

Ali, HA, Lippmann, M, Mundathaje, U, Khaleeq, G.. “Spontaneous Hemothorax: A Comprehensive Review”. Chest. vol. 134. 2008 Nov. pp. 1056-65. (Highly recommended review of spontaneous hemothorax.)

Ambrogi, MC, Lucchi, M, Dini, P, Mussi, A, Angeletti, CA.. “Videothoracoscopy for evaluation and treatment of hemothorax”. J Cardiovasc Surg (Torino). vol. 43. 2002. pp. 109-12. (Review of the role of VATS in the management of hemothorax.)

Inci, I, Ozcelik, Ulku T, Tuna, A, Eren, N.. “Intrapleural fibrinolytic treatment of traumatic clotted hemothorax”. Chest. vol. 114. 1998. pp. 160-5. (This article describes the role of intrapleural fibrinolytics in the treatment of retained blood clots.)

Brooks, A, Davies, B, Sethhurst, M. “Emergency ultrasound in the acute assessment of haemothorax”. Emerg Med J. vol. 21. 2004. pp. 44-46. (In a small prospective study of 61 trauma patents, ultrasonography has demonstrated sensitivity of 92% and specificity of 100% in diagnosing hemothorax.)

Liu, F, Huang, CY, Ng, YB, Hang, J.. “Differentiate pleural effusion from hemothorax after blunt chest trauma; comparison of computed tomography attenuation values”. Journal of Acute Medicine. vol. 6. 2016. pp. 1-6. (This study retrospectively looked at the chest CT scan attenuation of the pleural effusions to differentiate hemothorax from pleural effusion and empyema after blunt chest trauma. They found excellent accuracies with an area under the curve [AUC] of 0.964 [95% CI: 0.931~0.998] for HU values. The optimal cut off values were 15.6 HU [sensitivity: 86.8%; specificity: 97.4%]. To distinguish hemothorax from empyema, AUC of 0.866 [95% CI: 0.797~0.935] was obtained, with optimal cut off values of 15.9 HU [sensitivity: 86.8%; specificity: 71.2%].)

DuBose, J., Inaba, K., Okoye, O.. “Development of posttraumatic empyema in patients with retained hemothorax: results of a prospective, observational AAST study”. J Trauma Acute Care Surg. vol. 73. 2012. pp. 752-757. (A multicenter study of 328 trauma patients with retained hemothorax demonstrated an overall incidence of empyema of 26.8%. Of patients developing empyema after retained hemothorax, 94.3% required additional interventions, with many requiring two or more interventions beyond initial chest-tube insertion.)